| 摘要 |
The method determines laser stability of an optical material, which is suitable for making an optical element through which high-energy light passes. The method includes pre-irradiation to produce radiation damage and measurement of the resulting induced non-intrinsic fluorescence. The method is distinguished by excitation of induced fluorescence immediately after pre-irradiation and after at least ten minutes after pre-irradiation with light of a wavelength between 350 and 810 nm, and measurement and quantitative evaluation of fluorescence intensities at wavelengths between 550 nm and 810 nm. Especially laser-stable optical materials, particularly CaF<SUB>2 </SUB>crystals, have a normalized difference (Z) of the fluorescence intensities measured at a first time immediately after pre-irradiation and at a second time at least ten minutes after the pre-irradiation, as calculated by the following equation (1): <?in-line-formulae description="In-line Formulae" end="lead"?>Z=(I<SUB>2,lambda1,lambda2</SUB>-I<SUB>1,lambda1,lambda2</SUB>)I<SUB>2,lambda1,lambda2</SUB>, (1)<?in-line-formulae description="In-line Formulae" end="tail"?> which is less than 0.3.
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